TddAndConcurrency.Agile2008.Outline

Edit 0 5 …

Part 0

Begin running driver that exercises ObjectWithValue before the start.

At start, David Nunn will present himself and myself.

Part 1: Prove it's broken


  • Show trivial code example (ObjectWithValue)
  • Show results of running driver, the code is broken
  • Ask by table:
    • Help me demonstrate that this code is broken with a test
    • Here are a few candidate characteristics of a good test: Fast, Independent, Reliable, Self-validating, Timely. Which of these apply to your approach? Do all of these apply?
    • Start running demo in XP under Parallels so I can discuss those results
  • Poll Tables
    • Collect their ideas (added to results of workshop)
      • Ask if anybody has coded it and if so do they want to demo it?
      • If not, anybody want to pair on this?
      • Collect group testing ideas
    • Demo my test, walk through it. Run it with 2 threads, 10000 loops.
      • Run with OS X 1.5 and 1.6 JVM, run with Parallels-based XP running JDK ?
      • Relate examples from developing course
      • Discuss a few findings
      • Reduce numbers to 2 and 20 and then run it with ConTest
      • Question: How do we trade-off repeatability and fast in this context?

Part 2: Deadlock and Dining Philosophers


Problem: Imagine you have two pooled resources: one bucket of MQ connections and one bucket of database connections. Also imagine 4 operations: CRUD, each of which uses one connection and one database. Finally, assume these operations are fronted by some threaded environment, e.g. a web-server:
  • In your groups discuss the following:
    • Is deadlock possible?
    • Describe a specific scenario that causes it?
    • How can you guarantee it cannot happen?
    • How can you demonstrate deadlock occurring via a test?
    • How can you show that it probably isn't going to happen?
    • 10-minute table-top discussion

Dining Philosophers:
  • Describe the problem
  • Describe one solution
  • Describe the conditions for deadlock (summarize)
  • List the big three algorithms
  • Quesitons/Comments

Part 3: Refactorig to SRP to test


Show example system that is not performing.
  • How can I assert my desired goal
  • How can I approach it
  • How can I test for it?

What should I do to make this testable?